The present invention generally relates to color video signal recording and reproducing apparatuses, and more particularly to a color video signal recording and reproducing apparatus which simultaneously records and simultaneously reproduces a luminance signal and color difference signals on and from independent tracks of a recording medium.
There is a conventional color video signal recording and reproducing apparatus (hereinafter simply referred to as a recording and reproducing apparatus) which separates a color video signal into a luminance signal and two kinds of color difference signals, and compresses the time base of the two kinds of color difference signals into 1/2 the original time base. The two kinds of time-compressed color difference signals are alternately transmitted in time sequence as a time-compressed line-sequential color difference signal. The time-compressed line-sequential color difference signal and the luminance signal are frequency-modulated independently and are recorded simultaneously on and reproduced simultaneously from independent tracks of a recording medium.
According to this conventional recording and reproducing apparatus, since the time-compressed line-sequential color difference signal and the luminance signal are simultaneously reproduced from independent tracks of the recording medium, it is necessary to match the time bases of these reproduced signals. For this reason, a synchronizing signal is added to both the time-compressed line-sequential color difference signal and the luminance signal at the time of the recording, and the synchronizing signals are used when expanding the time base of the reproduced time-compressed line-sequential color difference signal back into the original time base at the time of the reproduction. A memory is used for expanding the time base of the reproduced time-compressed line-sequential color difference signal. Hence, at the time of the reproduction, the write-in of the reproduced time-compressed line-sequential color difference signal to the memory is carried out based on the synchronizing signal within the reproduced time-compressed line-sequential color difference signal, and the read-out from the memory is carried out based on the synchronizing signal within the reproduced luminance signal. The synchronizing signal within the reproduced luminance signal is different from horizontal and vertical synchronizing signals of the color video signal. The above described recording and reproducing apparatus is disclosed in a Japanese Laid-Open patent application No. 60-42997, for example.
Furthermore, in the conventional recording and reproducing apparatus, a certain interval is provided between a write-in clock pulse and a read-out clock pulse for the memory so that a predetermined inactive interval is provided between the write-in time period and the read-out time period. By providing this predetermined inactive interval, it is possible to prevent a signal dropout caused by partial overlap of the write-in time period and the read-out time period even when a jitter is generated between the two signals simultaneously reproduced from the independent tracks of the recording medium and even when a mechanical error exists between heads which carry out the recording and reproduction of the signals on and from the recording medium.
However, in the conventional recording and reproducing apparatus, the predetermined inactive interval is set to an extremely short time in the order of 2.5 .mu.sec, for example. As a result, when a dub-recording is carried out a plurality of times, the above described jitter and mechanical error between the heads are accumulated and it no longer becomes possible to prevent the partial overlap of the write-in time period and the read-out time period by the provision of the extremely short inactive interval.